The present invention relates to a method of wrapping cylindrical products.
In particular, the present invention relates to a method which may be used to advantage in the food industry for wrapping groups of cylindrical products, such as biscuits or sweets arranged side by side in such a manner as to form a cylindrical group.
Cylindrical-shaped products of the aforementioned type are known to be wrapped using a wrapping device usually comprising a conveyor consisting of a drum turning about is axis and having a number of substantially semicylindrical peripheral seats arranged parallel to the drum axis- Said drum is normally operated in conjunction with a first device for feeding portions of wrapping material, and a second device for feeding the products, which are inserted successively inside a respective said seat together with a respective portion of wrapping material.
Subsequent to insertion as described above, an intermediate portion of each portion of wrapping material is folded substantially in the form of a U between the surface of the seat and the outer surface of the product, and the two opposite end portions of the wrapping material projecting from the seat are folded by folding means into contact with the outer surface of the product, usually in such a manner as to partially overlap each other. Each seat (see, for example, British Patent Application No. 2.068.883) is usually provided with folding means comprising two mobile folding devices arranged on opposite sides of and travelling with the seat. By way of an alternative, simpler solution, the folding means of each seat comprise a single mobile folding device located upstream from the seat in the rotation direction of the drum, and which provides for folding into contact with the outer surface of the product the trailing end portion of wrapping material in relation to the travelling direction of the product, the leading end portion being folded by a single fixed folder located outwards of the outer periphery of the drum.
The above known wrapping device presents a number of drawbacks as a consequence of the folding devices assigned to each seat, which devices not only result in extremely complex and therefore high-cost, poorly reliable drum design, but also generally speaking, in poor grip between the folded end portions of wrapping material and the product. Moreover, as the vibration caused by the mobile peripheral masses consisting of the folding devices would be unacceptable at relatively high surface speeds, the speed of the products and respective seats must be kept relatively low.